Aiming devices for aiming telescopes conventionally have a glass reticle plate within the optical path of the aiming telescope. The reticle plate is arranged transverse to the optical axis of the telescope. An aiming mark is provided on or within the reticle plate, for example by means of etching or engraving. The aiming mark may have different shapes, for example the shape of a point, of one or more lines, of a cross hairs or the like.
In this context it is well known to illuminate the aiming mark by means of a light source in order to be able to aim also under bad light conditions.
Published U.S. patent application Ser. No. 2002/0080480 A1 (=DE 100 51 448 A1) discloses an illuminated reticle plate. This prior art reticle plate is provided with an essentially ring-shaped light guide being arranged around the reticle plate. The light of a diode is emitted into the light guide via a flat portion of the light guide and is coupled into the reticle plate over the entire periphery thereof with equal light distribution.
German Utility Model specification DE 299 03 989 U1 describes an aiming mark within a telescope which, as seen from the objective lens of the telescope, is arranged on the rear side of a beam splitter. An aperture stop is provided above the upper side of the upper prism of the beam splitter and a light source, i.e. a light-emitting diode (LED), is arranged above the aperture stop. The light beam delimited by the aperture stop impinges on the contact surface of the prisms as an aiming mark, for example as a light point.
In an aiming device according to European Patent Specification EP 886 163 B1(=DE 197 26 397 A1) the light is likewise irradiated into the narrow side of a reticle plate and is emitted therefrom perpendicular from its surface by means of a mark configuration consisting of a pattern of alternating transparent gaps and opaque ridges.
These prior art aiming devices have the common disadvantage that the light efficiency is quite poor. In some aiming devices there is also a considerable amount of stray light so that there is the risk that the image of the aiming object is overirradiated under poor light conditions. Further, these aiming marks may only be configured in a limited range of designs.
German Utility Model specification DE 94 20 382 U1 discloses an aiming telescope with an illuminated aiming device. The aiming device utilizes a reticle plate being worked from a circular glass plate. The reticle plate consists of a ring having three glass ridges projecting inwardly therefrom till close to the ring center and being spaced relative to each other in a circumferential direction by 90° each. Thereby, an aiming mark is configured being similar to the so-called“Mark No. 1”. The glass ridges are illuminated from the ring. At its free end, the middle glass ridge is pointed and the point is flattened, such that the flattened edge emits the irradiated light in an axial direction. The marksman sees this arrangement as a light-emitting arrow point.
In this prior art aiming device the light efficiency is better, however, the glass ridges positioned in the marksman's field of vision are disturbing. Moreover, the reticle plate is an extremely fragile element that can hardly be used under rough ambient conditions, as frequently occur during the practical use of aiming telescopes. Further, the glass ridges have to be manufactured with polished surfaces, because otherwise an uncontrolled emission of light would occur at the glass ridges' surfaces which would result in a considerable stray light. However, polishing is hardly possible in view of the filigree structure of the reticle plate.